Out-of-bounds write in Linux kernel - CVE-2026-89834
Published: September 17, 2026
Vulnerability identifier: #VU150446
CSH Severity: Low
CVSS v4: 0 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89834
CWE-ID: CWE-787
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to perform out-of-bounds I/O.
The vulnerability exists due to incomplete iteration over active curseg types in free_segment_range() when shrinking an F2FS filesystem. A local user can initiate a filesystem shrink operation while active in-memory curseg types reside in the target range to perform out-of-bounds I/O.
Non-persistent in-memory curseg types, including CURSEG_COLD_DATA_PINNED and CURSEG_ALL_DATA_ATGC, can remain in the truncated range.
Affected software
Linux kernel
How to mitigate CVE-2026-89834
Install security update from vendor's repository.